1. Field of the Invention
The present invention relates to a system for delivery of a stent into the body of a patient. More particularly, the present invention relates to an expansion-assisting delivery system for a self-expanding stent.
2. Description of Related Art
Stents are well-known endoprostheses. A conventional endoprosthetic stent includes a radially-expandable, tubular structure. The tubular structure can expand radially from a compact form for delivery to an expanded form for implantation. Radial expansion of the stent effects implantation into the tissues of a vessel wall being repaired or bridged. The vessel can include, for example, a body canal, blood vessel, duct, other passage, and the like.
A conventional endoprosthetic stent can be mechanically expansive or self-expansive. A conventional mechanically-expansive stent initially possesses a radially compact form. The stent is loaded onto a delivery system, such as a catheter. Typically, an expandable balloon is positioned in the tubular structure of the stent. After delivering the stent to the region of a vessel being repaired or bridged, the balloon is expanded, thereby implanting the stent onto the vessel wall. To expand the stent, the balloon must be connected to a fluid source by means of a lumen or some other tubular structure.
A conventional self-expansive stent initially possesses a radially-expanded form. The stent is compressed radially as it is assembled onto a delivery system. Typically, an outer tubular structure retains the compressed stent until it is delivered to the region of a vessel being repaired or bridged. The stent is then released from its compressed state and self-expands to implant onto the vessel wall. An expandable balloon is not required to expand the stent. However, in cases where a stricture of the vessel is difficult to repair or bridge, a physician may use a balloon to assist with expansion of the deployed stent.
Generally, when a balloon is used to assist with expansion of a self-expanding stent, the conventional stent delivery system is removed after the stent is successfully deployed. Then, either a separate single-use balloon catheter or a second delivery system having an expandable balloon is delivered to the sight of the stent. In either event, a physician would be slowed by this process of removing the stent delivery system and delivering the balloon.
Conventional stent delivery systems generally include a minimal transverse dimension so is that a distal end of the delivery system can be navigated through and along a patient's lumens, or vessels, either in a percantaneous insertion procedure or through the working channel of an endoscope or laparoscope. Often times, physicians use a delivery system in combination with a medical guidewire. Typically, in transluminal procedures, the physician directs a guidewire through narrow passages, or vessels, in a patient's body using a steering mechanism provided at a proximal end outside of the body. The physician monitors the travel and position of a distal end of the guidewire by a fluoroscope or other known device. Once the distal end of the guidewire reaches a desired position, the steering mechanism is removed and the delivery system is directed into the vessel along the guidewire. Other procedures for directing catheters or similar devices into larger vessels of the body, such as the esophagus, are also well known.
Thus, use of a conventional delivery system for a self-expanding stent in combination with a guidewire and a post-deployment expandable balloon would require the following time-consuming procedures: delivery of the guidewire; delivery and deployment of the stent; removal of the stent delivery system; delivery and activation of an expandable balloon device; and removal of the balloon delivery system and guidewire. The repeated insertion and removal of delivery systems prolongs the procedure and thereby increases the trauma and risk to the patient and increases costs.